The weighted synergetic speed control for single inverter, parallel-connected induction motor drive

Abstract

In the case of unbalanced load performance, the key issue in speed control of a single inverter-powered parallel motor coupling system is how to overcome the difference in motor parameters and the effect of slip between the induction motors to maintain the same speed. Based on the synergetic control theory and synergy manifold design techniques, the model which is field-oriented vector control with reduced order induction is proposed, as well as a synergetic control strategy. Moreover, the accuracy of the rotor flux observation is one of the most important steps in the motor control. In order to improve the convergence speed of rotor flux error, a new flux observer based on the sliding mode theory is proposed. Introducing the Sig function instead of the symbol function, the sliding mode control technology is improved to observe rotor to eliminate the control chattering. Then, two motor speed coupling weighted synergetic control models are given by using the new weight vector of the parallel induction motor. These models can directly obtain the stator excitation current and torque current of the two motors. The simulation and experimental results show that the newly proposed motor synergetic control method has better steady operation performance, overcomes the shortcomings of the existing average vector control method in load imbalance and motor parameter difference and proves the validity and advancement of the design strategy.